Piano tuning-pin.



J. F; OONOVER.

PIANO TUNING PIN.

APPLIOATIOK FILED we. 22, 1907.

921303. Patented May 11', 1909.

JAMES F. OONOVER, OF CHICAGO, ILLINOIS.

PEA-NO TUNING-PIN.

No. 921,203. Specification of Letters Patent. Patented May 11, 1909.

Application filed August 22, 1807. Serial No. 389,727.

To all whom it may concern:

it shown that i, inns F. COXOVER, a citizen oi the United States of America, and resident of Chicago, Illinois, have invented a c n new ul niprownient in luning-l'fins, of which the following is a My invention relates to improvements in stringing pianos, having pa ticular ren e nce to improvements in pins and means for se cur t i in position.

0 dc is the production 5 cl the tension of he piano y be varied without loosening the plus A further object is vice by means iwh'f. wood of the w vent the pin from turnin bacl pull e strin 's.

O C) 1 trier oh; i is the pro readily i duction of a deed in place in a elhr-iency oi the at can b, v,

A p m or object is the production of a deby means oi which the pins are prevented from enlarging the l .l s and destroying the resiliency of he iih of the wood of the wrcst- P91" object is the prod notion ol a device y means of which the contact of the sleeves and plus is such as to cause the pins to move easily and smoothly in the process of tuning the ins unicnt.

A further object is the production of a cevice of simple construction an d one that can be cheaply manufactured.

These and such other objects as may hereinafter appear are attained. by my device, embodiments of which are shown in the accompanying drawings, in which Figure 1 is a sectional view of a portion of a piano frame showing my improved device in position. Fig. 2 is a transverse sectional view taken through the pin in position.

Like numerals of reference indicate like parts in the several figures of the drawings.

Referring to the drawing by reference numerals, S designates the wrest-plank and the string. The strings are secured at their upper ends by being wound around the top portion of a pin 1]. provided with a squared head 12. The wrest planlz is provided with a series of holes 13 in which fit sleeves or sockets 14, and within which sleeves the tuning pins 11 are seated. These sleeves 14 l are formed from a single strip of metal havi ing corrugations l515 on their outer surface. The sleeve is preferably split, as shown at 16. A flange 17 is turned outwardly on the top of the sleeve, which provents the sleeve from falling through the wrest-plank. The inside of the pin sleeve forms a smooth surface.

The method of stringing the piano is as follows Holes are bored in the wrest-plank in proper position, and of a diameter fitting the outer diameter of the pin sleeve 14-. These pin sleeves are then placed in t is holes 13, the corrugations 1515 resting against the fiber of the wood surrounding the holes. The pin 11 is of a greater external diameter than the internal diameter of the sleeve 1-1, and is provided. with a rounded end 19. This end is inserted in the mouth of the pin sleeve, and the pin driven within the sleeve. By this operation, the sleeve is expanded. This operation forces the corrugations of the sleeve against the fiber of the wood and forces the :libers of the wood oi the i-rrcst plank into a resilient state, which in turn produces a counter force noon the sleeve clamping it upon the pin producing the friction which holds the pin from turning back under the strain of the string 9. The string 9 is rigidly secured at its lower end to the usual iitch pin and wound about the upper end in coils 20, as shown in Fig. 1. it will be noted that the last coil of the string is close to the flange 17 consequently the strain of the string is brought against the pin just above the top of the wrcst-plank By this means the danger of springing the pin (which would happen if the force were brought higher up on the pin) is avoided. The end of the pin is squared, as shown at 12, so that by means of a wrench the tension of the strings may be varied at will.

i ieretofore in stringing pianos, it has been customary to simply drive the tuning pin 1l*which was preferably formed with ininute threads into holes bored in the wooden wrestplank, trusting to the pressure of the wood against the pin to hold the pin securely in place. It is evident that in tuning the i piano, it is necessary to often turn the pin in botn directions,-that is, the tension of the string is often made greater than desired, necessitating the turning back of the pin. This necessarily loosens the pin within its wooden socket. Inasmuch there is in some cases a tremendous tension on these strings, runl l U larges the holes and destroys the resiliency of the wood. Vi "hen this enlargement of the holes amounts to say two or three one thousand tns of an inch, the pins rrill no longer s and, and l larger ones must be substituted. for this, tuning are genera v several sizes the diameters increasin thy five one thousandths of an inch. Zlc

i provide 1 1*: 131LLS or the gradual enlargement of the holes, the pins are driven as tightly into the p ain; ascan be without causing the pin to twist oil y-xhcn turned in tuning. Hence, in tuning the pisue, the force exerted to start the pin is so great that it usually causes the pin to move beyond the desired point, it must, therefore, be turned back in order to give the proper tension. i'his abrupt movement of the in makes it d suit to correctly tune the instrument. i 1th my invention, these defects are practically overcome. The tension of the strings can be varied Without loosening the pins, for the reason that the force which holds them in place is constant as the resiliency of the iiber of the rrrcstj plank is not destroyed by crushing while turning the pin under the strain of the string.

The pins turn easily and smooth y from i ternal diameter oi said sl eve senses the nature of the friction between the two 40 metal suritaces, and because the binding force need be no greater than ust enough to hold the pin from turning back under the strain of the string.

I. claim: 1. In a piano, the combination with a wrest-plank, a split cylindrical sleeve having a smooth inner surface, an irregular outer j surface sub-star tially parallel with the inner surface, an outwardly turned Lang-e formed on the upper end tl ereof, cylindrical pin having a smooth outer surface, aid a diameter greater than the internal diameter of said sleeve.

2. As a no ticl cylindrical sleeve face, an irregular out i parallel eitli the inner sui turned nange formed on the uppe" nd thereof, a cylindrical pin having sir- 0th outer (30 surface, and a diameter greater nan the in- 13s a new article of manufacture, a split cylindrical sleeve haying smooth inner surtically corrugated outer surface parallel with the inner suria ce, go formed on the e a cylindrical pin hayinga ter surfers, and a diameter greater than the internal diameter of said sleeve. Signed by me at Chicago, Illinois, this 31st day of July, 1907.

COi EVER.

VJitnesses:

NELLin Grass,

1 JENNIE holler. 

